I'm in middle school, and I like this girl. I'm a girl, how do I ask her out??

Choose the medium of communication you prefer - you can also write to her if it's more comfortable- and just tell her that you would enjoy her company and would like to spend some time with her outside of school. The rest will be up to her, and then hopefully with time you can both figure out with "enjoying each other's company" means for the other. I know it's hard, but it's worth trying!

Ask her out in a way you feel most comfortable doing so. You could call her, write her a note, text her, tell her face-to-face, etc. It is really up to you. Just stay true to yourself. If she says yes, then congrats! If she says no, that's ok too. She does not have to go out with you if she doesn't want to. Just remember that it is not the end of the world and that there are plenty of other people for you to meet. You have your whole life to find someone to date, so don't stress about being single now :)